The repeater is a device configured to gain the input signal. Normally, when the electrical signal is sent by the cable, the signal power is decreased as the length of the cable is increased. Hence, it needs a repeater for gaining the signal power so as to improve the transmitting distance of the signal. As the technology and the demand of the communication system for the users are both kept growing, the system structure becomes more and more complex, and the length of the cable is getting longer, too. As a result, the requirement of the repeater is increased.
However, the parameter configuration in the repeater is set by the pin mode which comprising four input states. Thus, there is limitation of the parameter configuration which is able to be disposed, and the state is probability switched to the adjacent states due to the outside interference. Furthermore, when the length of cable adapted to the repeater is changed, the parameter is not able to be change currently. Therefore, it needs to change the printed circuit board to adjust above situation.